Recently, along with the development of the liquid crystal display technologies, the competition in the liquid crystal panel industry becomes more and more fierce, so how to reduce the production cost of the liquid crystal display panel has become a leading option for manufacturers. In order to reduce the production cost, a gate driver circuit is generally arranged at a peripheral portion of a display panel. The gate driver circuit includes a plurality of shift registers, and each shift register corresponds to one gate line. These shift registers are connected in series, and there is a triggering signal transmitting from level to level between any two adjacent shift registers. Upon receiving the triggering signal, each shift register outputs a gate scanning signal to the corresponding gate line, and meanwhile transmits the triggering signal to a next-level unit circuit, so as to achieve a gate-driving function. In this way, it is unnecessary to provide a gate driver IC separately at a bezel region of the display panel, thereby to provide the display panel with a narrow bezel, reduce the production cost and improve the market competitiveness of the product.
Usually, an existing shift register has a circuit structure as shown in FIG. 1 and FIG. 2 shows a corresponding input/output sequence diagram. As shown in FIG. 2, when the shift register is normally turned on, a potential at a first node PU is pulled up within a first stage, and continues to be pulled up within a second stage, so as to turn on a switching transistor T7, thereby to enable a scanning signal output end to output a scanning signal. However, the first node PU outputs a voltage signal including noise (e.g., region A in FIG. 2), and a signal generated when the potential at the first node PU is pulled up at the first time has a relatively high potential, so during the charging and discharging by a capacitor C1, the scanning signal from the scanning signal output end may include a relatively large noise (e.g., region B in FIG. 2), resulting in a large power consumption for the circuit of the shift register as well as a reduced yield of the display panel.
Hence, there is an urgent need to reduce the noise included in the scanning signal from the shift register as well as the power consumption, thereby to improve the yield.